In U.S. Pat. No. 4,236,287 issued Dec. 2, 1980 to Bernard Smith for "Method of Making A Ruggedized High Current Density Cathode," there is disclosed and claimed a method of making such a cathode wherein a porous high purity tungsten pellet is impregnated with Ba.sub.5 Sr(WO.sub.6).sub.2, and an activator at about 1900 degrees C. in a dry inert gas atmosphere. The difficulty with the method of #4,236,287 is that the impregnation temperature required is too high to meet the emission and sublimation requirements of emitters required for high frequency microwave tubes. That is, during the impregnation step, there is a high loss of barium which limits the life of the cathode. Moreover, due to the high impregnation temperature, there is a loss of barium and activator which translates directly to a loss of beam density with subsequent difficulty in beam control in a linear beam device.